This is a beginner video lesson on the concept of square root and how it ties in with squares. The lesson suits grades 7-8 and pre-algebra, and is meant for initial instruction on the topic.
Finding a square root of a number is like finding the side of a square when the area is known. Square root symbol acts as a grouping symbol: anything under it is in parentheses and is solved first. I also solve a few problems involving the area & perimeter of squares.
Additionally, you can practice finding the square root of numbers here (online practice).